Use of urinary concentrations in mg/dl in relation to absolute values in 24-hour samples for the evaluation of lithogenic factors in stone forming patients. / Uso de las concentraciones urinarias en mg/dl en relación a los valores absolutos en 24 h para la evaluación de factores litogénicos en pacientes litiásicos.

OBJECTIVE: The aim of this study is to analyze urine concentrations (mg/dl) of different lithogenic factors in a sample of 24 h as a predictor of these changes rather than absolute values depend on the volume of diuresis. METHODS: A total of 131 patients from the North Almeria Health Management Area (Spain) with urinary calstone disease in whom a metabolic study was indicated were included from June 2014 to May 2015. The concentrations of calcium, oxalate, uric acid, citrate and magnesium were measured in the urine, and the calcium/citrate ratio was calculated. The classifications used were: hypercalciuria (>260mg/24h), hyperuricosuria (>750mg/24h), hyperoxaluria (>40mg/24h), hypocitraturia (<320mg/24h) and hypomagnesuria (<35mg/24h). The statistical analysis was performed using SPSS 17.0. RESULTS: A cut-off point of 12.55mg/dl, with a sensitivity of 90% and a specificity of 85% and a relative risk (RR) of 51.2 (13.9-188.4), was estimated for urinary calcium. For oxalate the cut-off point was 1.86mg/dl, with a sensitivity of 91% and a specificity of 84% with an estimated RR of 67.2 (8.3-540.6). As regards the uric acid concentration in urine, a cut-off point of 31.2mg/dl was estimated, with a sensitivity of 85% and a specificity of 70% and a RR of 12 (3.8-37.6). For citrate the cut-off point was 18.8mg/dl, with a sensitivity and specificity of 82% and 74%, respectively, with a RR of 13.7 (4.4- 42.6). The cut-off point for magnesium was 2.26mg/dl with a sensitivity of 95% and specificity of 78%, with a RR of 67.6 (11.4-398.3). CONCLUSION: The determination of urine concentrations, instead of absolute values, depends to a large extent on urine output, appears to be useful when estimating classic metabolic alterations and should be taken into account in the evaluation of patients with urinary stone disease.

Quercetin exerts a preferential cytotoxic effect on active dividing colon carcinoma HT29 and Caco-2 cells.

The effect of the naturally occurring flavonol, quercetin, was investigated on cell growth and metabolism of two human carcinoma cell lines, HT29 and Caco-2 cells, both during the exponentially growing phase and after confluence. Our results show clearly that, after a 48-h period of treatment, quercetin (in the range of concentration from 15 microM to 120 microM) exerted a preferential cytotoxic effect on active proliferating cells. This effect was dose dependent and was accompanied by a simultaneous inhibition of lactate release and a dramatic decrease of total cellular ATP content. In contrast, in confluent cells, quercetin failed to affect cell viability or lactate release, but led nevertheless to a depletion of cellular ATP level. In conclusion, the cytotoxicity of quercetin is markedly higher in actively growing cells in comparison with confluent cells.

Comparative effects of flavonoids on the growth, viability and metabolism of a colonic adenocarcinoma cell line (HT29 cells).

The aim of the present study was to compare the effect of five structural classes of flavonoids on the viability and metabolism of a colonic adenocarcinoma cell line (HT29 cells). The most prominent structural features of flavonoids favoring both their cytotoxic activity and their capacity to inhibit lactate release appear to be the desaturation of the 2, 3 bond and the position of attachment of the B ring. Indeed, flavonol and flavone are the most potent and, in both classes, the order of potency can be modulated by hydroxyl or methoxyl substituents. On the other hand, in our model, we did not find any correlation between flavonoid structure and their capacity to modulate cAMP level. This last point is discussed.

Relationship between flavonoid structure and inhibition of phosphatidylinositol 3-kinase: a comparison with tyrosine kinase and protein kinase C inhibition.

Depending on their structure, flavonoids display more or less potent inhibitory effects on the growth and proliferation of certain malignant cells in vitro, and these effects are thought to be due to inhibition of various enzymes. We investigated the inhibitory action of fourteen flavonoids of different chemical classes on phosphatidylinositol 3-kinase alpha (PI 3-kinase alpha) activity, an enzyme recently shown to play an important role in signal transduction and cell transformation. Of the fourteen flavonoids tested, myricetin was the most potent PI 3-kinase inhibitor (IC50 = 1.8 microM), while luteolin and apigenin were also effective inhibitors, with IC50 values of 8 and 12 microM, respectively. Fisetin and quercetin, as previously reported, were also found to significantly inhibit PI 3-kinase activity. The same flavonoids were also analyzed for inhibition of epidermal growth factor receptor (EGF-R), intrinsic tyrosine kinase and bovine brain protein kinase C (PKC). At elevated doses, some of these flavonoids were found to also cause significant inhibition of PKC and tyrosine kinase activity of EGF-R. A structure-activity study indicated that the position, number and substitution of the hydroxyl group of the B ring, and saturation of the C2-C3 bond are important factors affecting flavonoid inhibition of PI 3-kinase. They may also play a significant role in specificity of inhibition and could help to provide a basis for the further design of specific inhibitors of this lipid kinase. Finally, possible relationships between the antitumoral properties of these flavonoids and their biological activities are discussed.

Quercetin metabolites in plasma of rats fed diets containing rutin or quercetin.

We studied the bioavailability and the plasma transport of flavonols in rats fed quercetin or rutin diets. Wistar rats were fed one of the following purified diets for 10 d: control; 16.4 or 8.2 mmol rutin/kg diet; or 16.4, 8.2 or 4.1 mmol quercetin/kg diet. Flavonol concentrations were determined in plasma, ileal and cecal contents, and feces. In rats fed diets containing 16.4 mmol quercetin or rutin/kg, the concentration of circulating flavonols was approximately 115 mumol/L. Quercetin or rutin administration resulted in similar concentrations of quercetin in cecal contents. By HPLC analysis and beta-glucuronidase/sulfatase treatment, plasma flavonols have been identified as conjugated quercetin itself, or a conjugated form (4.5-fold as abundant) of an aglycone less polar than quercetin. Rats fed quercetin or rutin diets had a green/yellow-colored plasma that exhibited a peak absorbance at 411 nm, vs. 363 or 375 nm for pure rutin or quercetin solutions, respectively. This shift of band I absorption was obtained when pure quercetin was in the presence of albumin or added to a plasma fraction. The bathochromic properties of flavonoids in the presence of albumin are highly dependent on the presence of the C-2/C-3 double bond on the C-ring and are influenced by the degree of B-ring hydroxylation. The existence of intermolecular bonds between albumin and quercetin is supported by in vitro absorbance and fluorescence studies. With human albumin, the fluorescence intensity and the shift of quercetin absorbance increased in parallel to the albumin/quercetin molar ratio. Conjugated diene formation, resulting from Cu(2+)-catalyzed oxidation of human LDL or rat VLDL+LDL was effectively inhibited in vitro by 0.5 mumol/L quercetin. These results show that dietary flavonols are recovered in rat plasma as conjugated metabolites in non-negligible concentrations, and that these flavonols may be interesting antioxidant micronutrients with a variety of biological effects.